5 is a rather powerful array language, being a blend of APL and Forth inheriting the array processing features of APL and the stack based approach from Forth. The 5-interpreter is implemented in Perl using no special modules which makes the language highly portable (currently 5 runs on Mac OS X, OpenVMS, Windows and various LINUX systems). 5-programs tend to be very short, to be more or less loop- and conditional-free. The 5-interpreter is currently only about 2500 LOC and is a good example of the power of Perl when it comes to implement interpreters for various languages.